Tank circuit



NGV- 20, l945- l. E. MOUROMTSEFF ETAL 2,389,27l

TANK CIRCUIT Filed June 20, 1941 INVENTORS 56 5 40 I E Maz/wMrs-EFF y E?. /V//C-/C Z7 35 3g www ATTORNEY Patented Nov. 20, 1945 iTD STATES PATENT GFFICE TANK CIRCUIT Pittsburgh,

13 Claims.

Our invention relates to an 'ultra high frequency oscillator and especially to such an oscillator utilizing a hollow body resonator.

One of the difficulties with ultra high frequency oscillators is that as the frequency is increased there is diiiiculty in forming a necessary .tank circuit with means for properly adjusting this circuit and also there is diiiiculty in the satisfactory ad#- justment of the grid circuit. Another limitation on the use of increased high frequency is the limitation caused by Ithe nite transit time of the electrons.

We have solved these dimculties by utilizing the properties of hollow body resonators and combining these properties with the .three-element vacuum tube oscillator design andas a result have accomplished an ultra high frequency oscillator having adjustable output tank and grid circuits incorporated in suitable hollow body resonators. Other advantages will be apparent from the following description and drawing in which:

Fig. 1 is a view of the main cross section of a preferred embodiment of our invention. Figs. 2, 3 and 4 are views, respectively, of lines .II-l1, III-III and IV--IV of Fig. 1.

'Ihe cathode I0 of our device is preferably formed of a cage of wires more particularly described in our Patent 2,238,596, issued .April 15, 1941, for Ultra high frequency tube. This cathode. I has two leads II and I2 sealed through an insulating cylindrical portion I3 preferably of borosilicate glass. .As described in our patent the cathode has, as connections, a rod I9 and a sur rounding tube 20 extending to the leads II and I2 and separated by the insulator button 22. The upper portion of the cathode rod terminates in a disk I9' and tube in a disk 2li' perforated for the passage of the rod I9 therethrough. An insulator button 2|, also perforated for the rod I9, separates the two disks. The wires of :the cage are connected at each end to a different disk, the disk I9' being cut away for the passage of the wires from the disk 20'. The cage of wires forming the cathode I0 is surrounded in turn by ture I4 which is composed of a wires I5 secured at the top 'to a disc or plate It and supported by these wires I5 in a. plane perpendicular to the axis of the cathode and grid wires I0 and I5. The lower end of these wires is a grid strucplurality of grid secured in the rimof a metal cup-shaped member I 'I surrounding the base proper of the cathode and having an opening I8 suiilciently large for the passage of the cathode connections therethrough.

The cup-shaped member I'I is preferably composed of two members,

one of which forms the Pa., a corporation of Pennsylvania Application June 20,

1941, serian No. 398,910 (ci. 25o-27.5)

portion 23 to receive the wires and this is bound about the periphery of the inner member 24 havlng the lower base portion 25 containing the opening I8. The member 24 has preferably a long 5 tubular extension 26 integral therewith and ex tending for a considerable distance below the grid structure and having a bottom plate 2l welded thereto. A re-entrant annular member has its inner periphery 2a fastened to the outer wall of the .tubular grid extension 26 and its outer periphery 3U sealed vacuum tightto the adjacent edge of the insulation I3.

Surrounding .the active cathode and grid wires is a cylindrical anode 82 having an extended tubutance between the annular partition 35 and the closed end 34 of the anode extension is half a wave length of the desired standing waves to be produced in the hollow body resonator formed by the enclosed portion of the anode extension 33.

The lower .grid extension 26 from the lower base 25 to the closed end 2l is in excess of the half 30 wave length dimension of the anode 33. In order that .this grid extension may form a hollow body resonator tunable to the anode extension we preferably place a metal disk 3l in the lower portion of the grid extension and the adjustment.

The oscillations of the two cavities formed by 26 and 33 are coupled to each other by a feed back transmission line 50. An interior loop 5I in cavity loop 53 at one end of the transmission line 50. An interior loop 54 in the cavity 26 terminates in an exterior loop 55 adjacent a loop 56 at the other end of the .transmission line 50. The transmission line 5I! .preferably comprises a cylindrical conductwo pairs of loops 52, 55 feed-back arrangement is a coupling between the two resonators in addition to that provided by the internal electrode capacitance. This particular feed-back arrangement is illustrative as other types may be utilized such as a direct concentric transmission line with one or several tunable lateral lines to regulate the feed-back as to its amplitude and phase.

The output circuit preferably comprises a loop 4i attached to the upper portion of the inner Wall of the anode extension and having the other end pass through an opening 42 in the wall and an insulating plug I3 supported by an eyelet 44 on the side of the anode extension 33. A similar loop 45 may be formed on the exterior of the device for coupling to this type of transmission line.

The casing portionsof resonators are preferably copper, silver soldered together where necessary. The cathode is preferably thoriated tungsten and the cathode leads molybdenum.

The grid wires are preferably tantalum and the grid disc I6 molybdenum.

If desired, the anode portion and its hollow resonator extension 33 may conveniently be airor water-cooled. The potential difference between the cathode and anode may be any desired value and preferably from 1,000 to 10,000 volts. The cathode grid potential difference may be a sultable value and preferably approximately 100 volts difference. These high voltages can be more safely operated by having the anode at ground potential and the cathode at -1000 to 10,000. The grid will be correspondingly less negative. Inasmuchas the higher negative cathode leads Il and I2 extend through the casing at only one section illustrated in the drawing the negative high voltage at this particular portion can be effectively protected and there will be no danger to the operator from the ground potential of the anode extension 33. a

The operation of the device is that of the familiar 3-electrode oscillators formed by the cathode I0, grid I5 and anode 32 and feed-back arrangement. The oscillations of the grid will be reinforced by the tunable resonating hollow body extension 2 6 and these oscillations will be applied to the grid disc I6. The oscillatory voltage develops also between the disc i6 and the adjacent portion 36 of the anode resonator 33 thus producing oscillations in the cavity resonator 33.

The resonant properties of the grid and anode extensions will operate to provide an efficient and stable output from the device.

We have accordingly devised the high frequency oscillator which is capable of emciently utilizing very high frequencies. The entire tube elements are contained in a vacuum .tight envelope and there is no external radiation. The

device has an area to permit rapid and effective anode and also a careful and acgrid and anode. When of the outcooling of the curate adjustment of the this adjustment is set the frequency put is very stable.

Although we have described a preferred embodiment it is apparent that many modications may be made therein and accordingly we desire only such limitations to be imposed upon our invention as are necessitated by the spirit and scope of the following claims:

We claim:

l. A discharge device comprising a cathode, a grid and an anode,said grid having a disc secured thereto, said anode having an extension forming a closed-end hollow body resonator, said disc located in an opening in a wall of said hollow body resonator.

2. A discharge device comprising a cathode, a grid and an anode, said grid having a disc secured thereto, said anode having an extension with an outer closed end thereby forming a hollow body resonator. said disc located in an opening in a wall of said hollow body resonator and an extension or said grid with an outer closed end thereby forming a second hollow body resonator.

3. A discharge device comprising a cathode, a grid surrounding said cathode. and an anode surrounding said grid and cathode, a hollow body resonator `forming an extension of said grid in one direction and having an outer closed end, and a hollow body resonator forming an extension of said anode in another direction and an exterior feed-back transmission line between said resonators entering the same next said outer closed ends.

4i A discharge device comprising a cathode, a grid and an anode. said grid having a disc secured thereto, said anode having an extension with an outer closed end, thereby forming a hollow body resonator, said disc located in an opening in a wall of said hollow body resonator and an extension of said grid with an outer closed end thereby forming a second hollow body resonator, and an exterior feed-back transmission line between said resonators entering the same next said outer closed ends.

5. A discharge device having electrodes comprising a cathode, grid and anode forming a discharge space, two' of said electrodes having structure forming a closed-end hollow body resonator separate from said discharge space and one of said electrodes having an extension forming a second closed-end hollow body resonator separate from said discharge space, one of said resonators having means at its closed end to make its resonating length equivalent to that of the other resonator.

6. A discharge device having electrodes comprising a cathode, grid and anode forming a discharge space, two of said electrodes having structure forming a closed-end hollow body resonator separate from said discharge space and one of said electrodes having an extension forming a second closed-end hollow body resonator separate from said discharge space and an external feedback from one hollow body resonator to the other hollow body resonator.

7. A discharge device comprising a cathod a grid surrounding said cathode, and a cylindrical anode surrounding said .grid and cathode and `forming a discharge space therein, a disc at one end of said grid, an annular extension from said anode closely surrounding said disc, said anode having'a further extension with its outer end closed, thereby forming a hollowbody resonator with said annular extension and grid disc and on the opposite side thereof from said discharge space. 8. A discharge device comprising a cathode, a grid surrounding said cathode, and a cylindrical anode surrounding said grid and cathode and forming a discharge space therein, a disc at one end of said grid, an annular extension from said anode closely surrounding said disc, said anode having a further extension with its outer end closed, thereby forming a hollow body resonator with said annular extension and grid disc and on the opposite side thereof from said discharge space, said grid having an extension with its outer end closed, thereby forming a second hollow body resonator.

9. A discharge device comprising a cathode, a grid surrounding said cathode, and a cylindrical anode surrounding said grid and cathode and forming a discharge space therein, a disc at one end of said grid, an annular extension from said anode closely surrounding said disc, said anode having a further extension with its outer end closed, thereby forminga hollow body resonator with said annular extension and grid disc and on the opposite side thereof from said discharge space. said grid having an extension with its outer end closed, thereby forming a, second hollow body resonator and a feed back transmission line between said resonators.

10. A discharge devicecomprising an evacuated envelope, a cathode within the evacuated envelope, a control grid surrounding said cathode, an anodesurrounding said control grid and cathode, a closed-end hollow body resonator forming an extension of said control grid in one direction and constituting a part of said evacuated envelope, a closed-end hollow body resonator forming an extension of said anode in another direction and also constituting a part of said evacuated envelope, one of said resonators having means within the evacuated space thereof movable therein for adjusting the resonating length thereof. l

l1. A discharge device having an evacuated space and having electrodes comprising a cathode, control grid and anode forming a discharge space, two of said electrodes having structure forming a closed-end hollow body resonator separate from said discharge space but forming part of said evacuated space, and one of said electrodes having an extension forming a second closed-end hollow body resonator separate from said discharge space and also forming part of said evacuated space.

12. A discharge device comprising a cathode, control grid and anode forming a discharge space, said control grid having an extension forming a closed-end hollow body resonator, said hollow body resonator being completely partitioned oil electrically from said discharge space, said anode having an extension forming a second closed-end hollow body resonator, said resonators and discharge space being evacuated.

13. A discharge device comprising a cathode, control grid and anode forming a discharge space. said control grid having an extension forming a closed-end hollow body resonator, said hollow body resonator being completely partitioned od' electrically from said discharge space, said anode having an extension forming a second closed-end hollow body resonator, said grid having a portion in an opening in said second resonator, said resonators and discharge space being intercommuf nicating.

ILIA EMMANUEL MOUROMTSEFF. GEORGE M. DINNICK. 

